The present invention relates to the gel electrophoresis separation apparatus to analyze DNA, RNA or protein, and particularly to the sample holding device for fluorescence detection type DNA sequencer or the like, and to the sample injection method thereof.
DNA analysis uses gel electrophoresis. In recent years, there has been a widespread use of the apparatus which determines DNA sequences by fluorescence labeling of DNA and analyzing the DNA fragment length in real time. According to this apparatus, 0.1 mm to 0.3 mm thick polyacrylamide gel is formed in the gap between two sheets of glass, and is used as separation medium. Part of the gel top is made undulating to form sample injection wells. The sample is injected by the microsyringe into concave wells formed between sheets of glass.
In recent years, on the other hand, attention has been drawn to the method of using as separation medium the capillary gel, i.e. the gel formed in the capillary, in place of the slab gel. This is because high speed migration is enabled by providing high electric field since the capillary gel does not produce large joule's heat. Furthermore, electrophoresis systems provided with a great number of capillary gels have been developed. Such systems are disclosed, for example, in i) Kambara et al; Nature, vol. 361 (1993), pp. 565-566, ii) Mathies et al; Nature, vol. 359 (1992), pp. 167-169, iii) Takahashi et al; Japanese Patent Laid-Open 6-138037 (May 20, 1994) and iv) Takahashi et al; U.S. patent application Ser. No. 08/337,412 (Pending). According to this method, one end of the capillary is placed into the sample container, and voltage is applied between that end and another end of the capillary, thereby injecting DNA into the capillary by employing an electric field. Furthermore, v) Kambara; Japanese Patent Laid-Open-5-72177 (1991), vi) Kambara; U.S. Pat. No. 5,277,780 (Jan. 11, 1994) and vii) Kambara; U.S. Pat. No. 5,366,608 (Nov. 22, 1994) disclose an electrophoresis system wherein the capillary gels are connected to the sample injection holes at the side opposite to the sample injection side of the sample injection holes with which there is provided the sample injection plate having a great number of sample injection holes through which a great number of samples are injected.
Furthermore, viii) Kambara et. al; Bio/Technology, vol. 6 (1988), pp. 816-821 and ix) Kambara et. al; U.S. Pat. No. 4,971,677 (Nov. 20, 1990) show how the DNA fragments migrate in the gel.
The progress of genome analysis has come to require a great deal of the DNA base sequence determinations. This has resulted in the development of a DNA sequencer using the slab gel provided with a great number of migration lanes in the slab, and devices having many migration lanes with a great many capillaries arrayed. Despite increasing quantity of analysis, however, there has been a disadvantage of requiring much time and labor for the analysis, since the sample injection method has not been improved. Namely, in the slab gel apparatus, a great number of samples are injected one after another into the well by means of a microsyringe, requiring much time and labor.
According to the method using the capillary apparatus, on the other hand, the quantity of injected samples is about one hundredth of the samples stored in the sample container, with a great majority remaining unused. When the titer plate having holes exhibiting two-dimensional distribution for adjustment of the samples, it has not been possible to utilize the simplified method of controlling the temperature by pressing the capillary against the temperature controlled plate; this has disadvantageously been very inconvenient. Furthermore, electrophoretic injection of samples into the capillary gel to allow them to migrate has disadvantageously resulted in the tip end being damaged, which cannot be re-used.